浮动Div没有出现在IE7中

Question

以下js代码用于浮点div。它被称为“浮动ISI”，根据用户滚动的距离而消失。尽管采取了预防措施，但代码在IE 7中不起作用。想知道是否有人可能知道可能存在的问题。

var floating_isi = {
ids: function (staticISI, floatingISI) {
    this.staticISI = document.getElementById(staticISI); ;
    this.floatingISI = document.getElementById(floatingISI);
    this._floatISI();
    $(window).scroll(function () {
        floating_isi._floatISI();
    });
},
_floatISI: function () {
    var myHeight = 0; // var for height of browser window

    // window.innerWidth does not work in IE8 and below so we check if it gives us a number or not
    if (typeof (window.innerWidth) == 'number') {
        // it does work so we're not on IE8 or below
        myHeight = window.innerHeight;
    } else if (document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) {
        //IE 6-8 in 'standards compliant mode'
        myHeight = document.documentElement.clientHeight;
    };

    var T = 0; // T = distance between static ISI and top of browser window
    T += this.staticISI.offsetTop;

    if (window.pageXOffset !== undefined) {
        // pageYOffset = how many pixels down has been scrolled from original top of site                   
        T -= pageYOffset;
    } else {
        //IE8 and below do not have pageXOffset so we use this method
        var d = document.documentElement, b = document.body;
        T -= (d.scrollTop + b.scrollTop);
    }

    var difference = (T - myHeight); // distance between static ISI layer and height of browser window

    var floatingISIHeight = $(this.floatingISI).height() * -1;

    // uncomment for debugging, this renders on the hover ISI layer
    //console.log("T = " + T + " myHeight = " + myHeight + " difference = " + difference+" FloatingISIheight= "+floatingISIHeight);

    // if the difference between the layers is a certain value, then show/hide layers
    if ($(this.staticISI).is(':visible')) {
        if (difference <= floatingISIHeight) {
            $(this.floatingISI).hide();
        } else {
            $(this.floatingISI).show();
        }
    }
}

};